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Selection
Procedure
PKG-PRC002-EN12
Following is a sample selection for a
standard applied water-cooled self-
contained at particular operating
conditions. Use Trane Official Product
Selection System, TOPSS
™
, for making
all final selections or contact your local
Trane representative.
Unit Capacities
1
Determine entering air temperature dry
bulb and wet bulb and entering water
temperature.
2
Refer to the Performance Data section
beginning on page 32 to find gross total
and sensible capacity that best meets
capacity requirements.
3
Apply the cfm correction factors from the
capacity correction factor Table
PD-1 on page 31 to determine gross total
and gross sensible capacities at desired
cfm.
4
Multiply condenser water delta T by
the total capacity cfm correction factor to
determine new condenser water delta T.
5
Using design cfm, determine static air
pressure drops for accessories from the
air pressure drop Charts PD-1 through
PD-18. Add accessory static pressure
drops to external supply and return static
air pressure drops. Use the total air
pressure drop to determine rpm and
brake horsepower requirements from the
appropriate fan curve. Note: The fan
curves include refrigerant coil and internal
cabinet static loses.
6
Calculate supply fan motor heat by using
the following equation:
Fan motor heat (MBh) = 2.8 x fan motor
brake horsepower
7
Determine net total capacity and net
sensible capacity by subtracting fan
motor heat from gross total capacity and
gross sensible capacity.
8
Refer to Trane psychometric chart to
determine leaving air temperatures.
Waterside Economizer Capacity
1
After determining that the unit will meet
the required mechanical cooling capacity,
determine the waterside economizer
capacity by referring to the appropriate
two-row (low capacity) or four-row (high
capacity) waterside economizer capacity
tables on pages 32-58.
2
Determine entering air temperature dry
bulb and wet bulb, condenser water flow
(gpm), and economizer entering water
temperature.
3
Refer to the appropriate waterside
economizer table to find gross total and
sensible capacity and the leaving water
temperature.
4
Apply the cfm correction factor for the
waterside economizer from the
appropriate table to determine the gross
total and sensible capacities at the desired
cfm.
5
Multiply the condenser water delta T by
the total capacity cfm correction factor to
determine the new delta T.
6
Calculate supply fan motor heat by using
the following equation:
Fan motor heat (MBh) = 2.8 x fan motor
brake horsepower
7
Determine net total and sensible capacity
by subtracting fan motor heat from gross
total and sensible capacity.
8
Refer to the Trane psychometric chart to
determine leaving air temperatures.
Self-Contained